A vehicle air-conditioning apparatus that includes a refrigeration cycle including a compressor, a condenser, a pressure reducing device and an evaporator, and that performs fault diagnosis on appliances configuring the refrigeration cycle is conventionally used (for example, see Patent Literature 1). In Patent Literature 1, deterioration of the evaporator is determined first thing in the morning before a vehicle leaves a shed or before an air cooling season starts, based on sensor detection values detected by a pressure sensor and a temperature sensor installed in the vehicle air-conditioning apparatus.